How albatrosses get airborne at sea

Wandering albatrosses are one of the farthest-flying birds on Earth; some studies estimate that certain individuals may circumnavigate the southern ocean multiple times each year, covering over 100,000 kilometres in the process. Some of that flying prowess is down to their huge wingspan and ability to soar on air currents to stay aloft with relatively little effort. But they do have to descend periodically to land on the ocean surface to feed, and how they get airborne again is more of a mystery. Now, thanks to the University of Tokyo’s Leo Uesaka, we have a better idea. As he explains to Chris Smith, by equipping the birds with monitoring backpacks to track their trajectories he’s been able to show that they use the prevailing wind, and waves, to launch themselves back up into the air…

Leo - Albatross is known as largest seabird on earth. Its wingspan actually reach like three metres or more. So they can fly very efficiently. They usually use the ocean winds to fly.

Chris - That's a lot isn't it? Because we think pterosaurs, way back at the time of the dinosaurs, they had an 11 metre wingspan. Mm-Hmm <affirmative>. But three metres is still very, very large. Yeah. How much does an albatross weigh?

Leo - It's about nine kilograms to 11 kilograms.

Chris - And where are they distributed?

Leo - They're usually distributed around the Indian ocean or we call the sub Antarctic area like 30 to 50 degrees south.

Chris - And do they spend their entire life at sea or do they have periods when they come towards land? What's their average year?

Leo - They breed once in a year around the Indian oceans island.

Chris - And what was the unknown then that you felt that this study was able to address?

Leo - We don't know how their fine scale behaviour like taking off is affected by ocean environment.

Chris - Presumably - because they eat fish, don't they? - presumably there are gonna be periods when they have to come down to the water and land Yeah. Yes. To, to catch their prey and then they've got a problem of taking off again. And so yeah. Is is that one of the issues then that we need to understand that a bit better?

Leo - Yeah, taking off is quite energy consuming behaviour for albatrosses. So we need to find how the taking off effort change along the changing environment.

Chris - How did you do that?

Leo - We tagged small devices on albatrosses and tracked their motion and we also estimated their surrounding environment like winds and waves from their motion records.

Chris - How did you get the devices on the albatrosses in the first place? Did you have to go out to sea to do that?

Leo - We attached the small tags on their backs using a waterproof tape and recapture it again. And recover the tags.

Chris - And those tags. What data do they collect?

Leo - We mainly use the GPS data and acceleration data in this study.

Chris - And what was the question you were asking?

Leo - Well, my question is how severe weather they experience when they take off from the sea surface and how the takeoff effort change in the various environment. Like if the wave is quite high, how the albatros is taking off efforts changed.

Chris - And how did that then enable you to form a picture of what their behaviour is under these different environmental conditions?

Leo - They're taking off effort actually decreased under a high wave condition or windy wave condition. And only when wind and waves are quite gentle, their takeoff effort increased. Wind and wave helps their taking off.

Chris - When a pilot takes off in an aircraft, they point into the wind if they can to get more wind over their wings and more lift. Do the birds do the same, do they use the ambient conditions to help them?

Leo - Yeah, we also find that they always take off into the wind so that they can get enough lift force.

Chris - I can understand why the wind helps them get airborne, but why does wave action help as well? Is it literally because they're higher off the water at certain points and so they've got almost a launch pad?

Leo - I still don't have any clear explanation and any clue, but I, we, we guess that a higher wave condition makes a complicated wind condition right over the ocean surface and the complicated wind condition may help the albatross in taking off, even in very weak wind condition.